Method, apparatus, and computer readable medium to reproduce a 2-channel virtual sound based on a listener position

• US 20060062410A1
• Filed: 05/19/2005
• Published: 03/23/2006
• Est. Priority Date: 09/21/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Sun-min, Lee, Joon-hyun
• Granted Patent: US 7,860,260 B2
• Time in Patent Office: Days
• US Class Current: 381/310
• CPC Class Codes: H04S 2400/01 Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
• CPC Class Codes: H04S 3/00 Systems employing more than two channels, e.g. quadraphonic H04S5/00, H04S7/00 take precedence
• CPC Class Codes: H04S 7/302 Electronic adaptation of stereophonic sound system to listener position or orientation H04S7/301 takes precedence

Abstract

A method of reproducing a virtual sound and an apparatus to reproduce a 2-channel virtual sound from a 5.1 channel (or 7.1 channel or more) sound using a two-channel speaker system. The method includes: generating a 2-channel virtual sound from a multi-channel sound, sensing a listener position with respect to two speakers, generating a listener position compensation value by calculating output levels and time delays of the two speakers with respect to the sensed listener position, and compensating output values of the generated 2-channel virtual sound based on the listener position compensation value.

Claims

1. A method of reproducing a virtual sound, the method comprising:

generating a 2-channel virtual sound from a multi-channel sound;

sensing a listener position with respect to two speakers;

generating a listener position compensation value by calculating output levels and time delays of the two speakers based on the sensed listener position; and

compensating output values of the generated 2-channel virtual sound based on the generated listener position compensation value.

2. The method of claim 1, wherein the sensing of the listener position comprises measuring an angle and a distance of the listener position with respect to a center position of the two speakers.

3. The method of claim 2, wherein the angle is positive when the center position of the two speakers is located to the right of the listener position, and the angle is negative when the center position of the two speakers is located to the left of the listener position.

4. The method of claim 1, wherein the generating of the listener position compensation value comprises calculating the output levels and time delays of the two speakers based on the distance and the angle between the listener position and the center position of the two speakers.

5. The method of claim 4, wherein the output levels and time delays of the two speakers are calculated by one of the following:

6. The method of claim 1, wherein the compensating of the output values of the generated 2-channel virtual sound comprises adjusting levels and time delays of the generated virtual sound to be suitable for the listener position based on the generated listener position compensation value.

7. The method of claim 6, wherein a left channel level value X_L of the virtual sound is compensated by y_L(n)=gx_L(n−

Δ

), y_R(n)=x_R(n)

when the measured angle θ

is positive, and a right channel level value X_R is output as is, and the right channel level value X_R of the virtual sound is compensated by

$y_L<br><br>\left(n\right)=x_L<br><br>\left(n\right),y_R<br><br>\left(n\right)=\frac{1}{g}<br><br>x_R<br><br>\left(n-\mathrm{\Delta <br><br>}\right)$

when the measured angle θ

is negative, and the left channel level value X_L is output as is.

8. The method of claim 1, wherein:

the generating the 2-channel virtual sound from the multi-channel sound comprises continuously generating the 2-channel virtual sound;

the sensing of the listener position with respect to the two speakers comprises continuously sensing the listener position with respect to the two speakers; and

the generating the of listener position compensation value comprises calculating the output levels and time delays of the two speakers based on the sensed listener position whenever a change in the listener position is sensed.

9. A method of reproducing a virtual sound, the method comprising:

producing a virtual sound in a speaker system; and

adjusting the produced virtual sound according to a listener position change whenever a listener changes position within the speaker system.

10. The method of claim 9, wherein:

the producing of the virtual sound comprises creating a sound image at a predetermined listening position; and

the adjusting of the produced virtual sound comprises creating the sound image at an actual listener position that is different from the predetermined listening position.

11. The method of claim 9, wherein the adjusting of the virtual sound comprises maintaining a stereoscopic sound regardless of a listener position.

12. The method of claim 11, wherein the speaker system comprises a first speaker and a second speaker, and the producing of the virtual sound comprises:

receiving a plurality of channel signals corresponding to a multi-channel speaker system; and

determining a first virtual sound signal to be output by the first speaker and a second virtual sound signal to be output by the second speaker according to one or more head related transfer functions that depend on a predetermined listening position within the speaker system.

13. The method of claim 12, wherein the adjusting of the virtual sound comprises:

sensing a listener position with respect to the first and second speakers; and

adjusting at least one of the first and second virtual signals according to the sensed listener position.

14. The method of claim 13, wherein the adjusting of the at least one of the first and second virtual signals comprises adjusting at least one of:

a gain of the at least one of the first and second virtual signals; and

a delay of the at least one of the first and second virtual signals.

15. The method of claim 14, wherein the gain of the at least one of the first and second virtual signals is adjusted according to:

16. The method of claim 14, wherein the delay of the at least one of the first and second virtual signals is adjusted according to:

Δ

=|integer(F_s(r₁−

r₂)/c)

where F_s represents a sampling frequency, r, is a distance between the first speaker and the listener position, r₂ is a distance between the second speaker and the listener position, c is a speed of sound, and |integer| is a function that rounds to a nearest integer.

17. The method of claim 9, wherein the adjusting of the virtual sound comprises:

sensing a listener position in the speaker system;

selecting a speaker that is closest to the listener position; and

adjusting a virtual signal of the selected speaker according to;

Y(n)=g*x(n−

Δ

)

where x(n) is the virtual signal, g is an adjusted gain factor, Δ

is an adjusted delay value, and Y(n) is an adjusted output virtual signal.

18. The method of claim 9, wherein the producing of the virtual sound in the speaker system comprises one of:

producing two channel signals having virtual sound from a 5.1 channel signal; and

producing two channel signals having virtual sound from a 7.1 channel signal.

19. A method of reproducing a virtual sound while maintaining a stereoscopic sound regardless of position where the sound is being received, the method comprising:

determining virtual sound signals to reproduce at least three channel signals in a two-speaker system according to one or more head related transfer functions determined at a sweet spot of the two-speaker system; and

applying a position-specific compensation factor to account for a distance between the sweet spot of the two speaker system and a position of where the sound is being received.

20. A virtual sound reproducing apparatus, comprising:

a virtual sound signal processing unit to process a multi-channel sound stream into 2-channel virtual sound signals; and

a listener position compensator to calculate a listener position compensation value based on a listener position and to compensate output levels and time delays of the 2-channel virtual sound signals processed by the virtual sound signal processing unit based on the calculated listener position compensation value.

21. The apparatus of claim 20, wherein the listener position compensator comprises:

a listener position sensor to measure an angle and a distance of the listening position with respect to a center position of two speakers;

a listener position compensation value calculator to calculate output levels and time delays of the two speakers based on the distance and the angle between the listener position and the center position of the two speakers sensed by the listener position sensor; and

a listener position compensation processing unit to compensate the 2-channel virtual sound signals based on the output levels and time delays of the two speakers calculated by the listener position compensation value calculator.

22. An apparatus to reproduce a virtual sound, comprising:

a virtual sound signal processing unit to produce a virtual sound in a speaker system; and

a listener position compensation unit to update the produced virtual sound whenever a listener changes position within the speaker system according to the listener position change.

23. The apparatus of claim 22, wherein the listener position compensation unit maintains a stereoscopic sound regardless of a listener position.

24. The apparatus of claim 23, wherein:

the speaker system comprises a first speaker and a second speaker; and

the virtual sound signal processing unit comprises;

an input unit to receive a plurality of channel signals corresponding to a multi-channel speaker system, and

one or more virtual sound filters to determine a first virtual sound signal to be output by the first speaker and a second virtual sound signal to be output by the second speaker according to one or more head related transfer functions that depend on a predetermined listening position within the speaker system.

25. The apparatus of claim 24, wherein the listener position compensation unit comprises:

a listener position sensor to sense a listener position with respect to the first and second speakers; and

a listener position compensation value calculator to calculate a compensation value to adjust at least one of the first and second virtual signals according to the sensed listener position, wherein the listener position is defined by an angle and a distance from a point between the first and second speakers.

26. The apparatus of claim 25, wherein the compensation value adjusts the at least one of the first and second virtual signals comprises by adjusting at least one of:

a gain of the at least one of the first and second virtual signals according to the listener position and characteristics of a listening space; and

a delay of the at least one of the first and second virtual signals according to the listener position and the characteristics of the listening space.

27. The apparatus of claim 22, wherein the listener position compensation unit updates the virtual sound by sensing a listener position in the speaker system, selecting a speaker that is closest to the listener position, and adjusting a virtual signal of the selected speaker according to Y(n)=g*x(n−

Δ

), where x(n) is the virtual signal, g is an adjusted gain factor, Δ

is an adjusted delay value, and Y(n) is an adjusted output virtual signal.

28. A speaker system, comprising:

a virtual sound signal processing unit to produce a virtual sound; and

a sound reception position compensation unit to adjust the produced virtual sound whenever a sound reception position changes according to the sound reception position change.

29. A computer readable medium having executable code to reproduce a virtual sound, the medium comprising:

a first code to generate a 2-channel virtual sound from a multi-channel sound;

a second code to sense a listener position with respect to two speakers;

a third code to generate a listener position compensation value by calculating output levels and time delays of the two speakers based on the sensed listener position; and

a fourth code to compensate output values of the generated 2-channel virtual sound based on the generated listener position compensation value.

30. A computer readable medium having executable code to reproduce a virtual sound, the medium comprising:

a first code to produce a virtual sound in a speaker system; and

a second code to update the produced virtual sound whenever a listener changes position within the speaker system according to the listener position change.